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Calculation of the inactivation cross section of v79 cells by protons in radiotherapy
Faika A Azooz1, Thamer J Alkhalidy
1Department of Physics, College of Education, University of Mosul, Iraq.
Objective:
For efficient applications of protons in radiotherapy, detailed knowledge of the corresponding radiobiological mechanism is necessary. The inactivation cross section is a useful tool to explore the interaction mechanism. Hence, the inactivation cross section for proton irradiation on V79 cells has been calculated using published survival data.
Method:
The linear quadratic equation was used to fit the survival curves and the parameter α was used to calculate the cross section. The cross section σ is plotted as a function of the mean free path λ and the linear energy transfer LET.
Results:
The cross section σ-versus-λ curve shows a saturation region between λ≥2 nm and λ≤5 nm. In this region, the inactivation cross section value is about the same as the geometrical area of the DNA segment (≈4 μm(2)). Such a saturation is also seen in the σ-LET curve.
Conclusion:
This implies that one DNA segment is at a risk upon the traversal of a single proton.
